JPH09187031A - Video signal processing circuit for dubbing use video tape recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a circuit and to reduce cost by employing only one comb- line filter for the video signal processing circuit for a dubbing use VTR. SOLUTION: This video signal processing circuit for a dubbing use VTR is provided with a reproduction side VTR 50, a recording side VTR 51 has a comb-line filter 4 for eliminating crosstalk used for a reproduction color signal processing section 16-A, a switch SW1 is provided to an input side of the comb-line filter 4 and a switch SW2 is provided to an output side of the comb-line filter 4 and the switches 1, 2 are interlockingly switched depending up on the operating state of the VTR as to whether in the recording or the reproducing state. The comb-line filter 4 acts like a comb-line filter for a reproduction color signal processing section for the reproduction side VTR in the case of dubbing signal from the reproduction side VTR 50 by the recording side VTR 51 or acts like a comb-line filter for the reproduction color signal processing section of the recording side VTR in the case of reproducing the dubbed signal by selecting the switches SW1, SW2 interlockingly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the field of video tape recorders (hereinafter referred to as VTRs), for example, two V tape recorders.
The present invention relates to a video signal processing circuit of a so-called dubbing VTR in which TRs are arranged in a single housing to enable copying and editing of video signals and audio signals. In recent years, camera-integrated VTRs have become remarkably popular, and the reason why dubbing VTRs are sold is because it is convenient for editing tapes recorded by the camera-integrated VTR.

With the spread of dubbing VTRs,
It is intended to simplify the video signal processing circuit and reduce costs accordingly.

[0003]

2. Description of the Related Art FIG. 2 is a block diagram of a conventional dubbing VTR. This figure is a block diagram showing the connection and main configuration of a video signal processing circuit of a conventional home-use dubbing VTR which has two conventional VTRs arranged in one housing and has a function of editing a tape. In the figure, reference numeral 50 is a reproducing side VTR, and 51 is a recording side VTR. Playback VTR
Is an 8 mm system including the HI-8 system, and the recording side VTR
Is generally a VHS system.

The operation of the configuration shown in this figure will be described in detail below. In the reproducing VTR 50, the electric signal read by the rotary magnetic head 11 is taken out from the recorded tape 10 and amplified by the preamplifier 12 to a predetermined size. The amplified output is supplied to a high pass filter (HPF) 13 and a low pass filter (LPF) 14 for separating a luminance signal and a chrominance signal. The high pass filter 13 is for separating a luminance signal (Y signal), and the low pass filter 14 is for separating a color signal (C signal).

The output of the HPF 13 is given to the luminance signal reproduction processing circuit 15, and the output of the LPF 14 is given to the color signal reproduction processing circuit 16. The luminance signal reproduction processing circuit 15 demodulates the luminance signal (Y signal) and performs processing such as de-emphasis and noise canceller. On the other hand, the color signal reproduction processing circuit 16
Converts the color signal (C signal) to the original frequency. The luminance signal reproduction processing circuit 15 and the color signal reproduction processing circuit 16
Are supplied to a mixer (MIX) 17, then mixed and supplied to a terminal 18 as a composite video signal.

On the other hand, in the VTR 51 on the recording side, the composite video signal given to the terminal 18 is a low-pass filter (LP
F) 19 applies a luminance signal to a bandpass filter (BP
F) 21 separates the color signals. The luminance signal is frequency-modulated by the luminance signal recording processing circuit 20 and subjected to processing such as emphasis, while the color signal is converted to a low frequency by the color signal recording processing circuit 22.

The signals processed and converted by the luminance signal recording processing circuit 20 and the chrominance signal recording processing circuit 22 are mixed by a mixer 23, amplified by a recording amplifier 24, and passed through a magnetic head 25 to a magnetic tape 26. Recorded in.
The recording side VTR 51 is also provided with reproduction signal processing circuits (27 to 34) for reproducing the signal dubbed as described above or the recorded tape. That is, 27 is a rotary magnetic head, 28 is a preamplifier, 29 is a high-pass filter (HPF), 31 is a low-pass filter (LPF), 30
Is a luminance signal reproduction processing circuit, 32 is a color signal reproduction processing circuit,
33 is a mixer and 34 is an output terminal. Since these operations are almost the same as the operations of the above-mentioned reproduction side VTR 50, the description thereof will be omitted, but the main difference is in the band of the low-frequency conversion color signal frequency and the frequency-modulated luminance signal described below.

3A and 3B are detailed block diagrams of the operation of the color signal reproduction processing circuit in FIG. (A)
6B is an internal block diagram of the color signal reproduction processing circuit 16 of the reproduction side VTR 50, and FIG. 9B is an internal block diagram of the color signal reproduction processing circuit 32 of the recording side VTR 51. In (A), the low-pass conversion color signal fLS separated by the LPF 14
AC is an AC controlled so that its signal level is constant
It is input to the C circuit 1. This signal has a time-axis fluctuation component ΔfH due to cylinder rotation fluctuation, but in the next frequency converter 2, the conversion signal (fSC + fLSC + ΔfH) from the local oscillator including this fluctuation component causes
It is offset and converted to high frequency.

Further, the BPF 3 is for removing unnecessary components generated in the frequency converter 2 and separating the high frequency conversion color signal fSC. Further, the comb filter 4 in the next stage is used for removing crosstalk from adjacent tracks in the low-pass conversion color signal recording system. In this way, the processed signal is guided to the mixer 17 and added to the reproduction luminance signal as described above.

In this example, when handling a television signal of the NTSC system, the reproduction side VTR 50 is of the 8 mm system, and thus the low frequency conversion color signal frequency fLSC is 743 kHz,
The color signal frequency fSC is 3.58 MHz. In (B), this operation is almost the same as the content described in the description of (A), but different points will be described. Since the recording-side VTR 51 uses the VHS system, the low-frequency conversion color frequency fLSC is 62.
9 kHz, final processed color signal frequency fSC is NTS
It is 3.58 MHz of the C signal. Therefore, the frequencies of the conversion signals input to the frequency converter 6 are different, and the characteristics of the BPF 7 excluding the unnecessary components generated thereby are also different.

[0011]

In the above configuration, one VTR unit is dedicated for reproduction and the other is integrated as a recordable and reproducible VTR unit to form one VTR. In the dubbing VTR having such a configuration,
Only the reproducing side and the recording side were arranged, and a sufficiently rational circuit design was not considered.

It is an object of the present invention to provide a dubbing VTR having a rational configuration and a video signal processing circuit thereof by sharing a comb filter for color signal processing used during reproduction. is there.

[0013]

SUMMARY OF THE INVENTION The present invention is a video signal processing circuit of a dubbing tape recorder having a reproduction side tape recorder section and a recording side tape recorder section, wherein a reproduction color signal is provided in the video signal processing circuit. One comb filter for crosstalk removal used in the processing section is provided, input switching means is provided on the input side of the comb filter, and output switching means is provided on the output side, and the input switching means and the output switching are provided. The means is adapted to be interlocked with each other depending on the usage state of the tape recorder for reproduction or recording, and the comb filter is interlocked with the input switching means and the output switching means so as to be switched over to the reproducing side. When dubbing the signal from the tape recorder unit to the recording-side tape recorder unit, the comb-shaped filter of the reproducing color signal processing unit for the reproducing-side tape recorder is used. Operates as a motor, when dubbing of the recorded signal reproduction is characterized by operating as a comb filter of the reproduced chrominance signal processor for recording side tape recorder.

As described above with reference to FIGS. 3A and 3B, conventionally, a comb filter is conventionally provided in each of the color signal reproducing circuit of the reproducing side VTR and the color signal reproducing circuit of the recording side VTR, and the reproducing side VTR 50 and The recording side VTR 51 was used separately, but in the present invention, the comb filters are integrated into one. Switching means is provided on each of the input side and the output side of the comb filter, and these switching means are interlocked with each other depending on the operating state of the dubbing VTR. With such a circuit configuration, only one comb-shaped filter, which was required in the past, can be used with one, so that the cost can be significantly reduced as compared with the conventional one.

[0015]

1 is a block diagram of a video signal processing circuit according to the present invention. The broken line portion 52 is a VT for dubbing
The entire R is shown. The changes from FIG. 2 are as follows.
An 8-mm color signal reproduction processing circuit 16 without the comb filter 4 is designated as 16-A, and a comb SW is provided with a switch SW1 as an input switching means and a switch SW2 as an output switching means on the output side. Shape filter 4
(Or 8) is connected. The middle point of the switch SW1 is connected to the input end of the comb filter 4 and the switch S
The color signal reproduction processing circuit 16 is provided on one D side of the selection terminal of W1.
-Connected to A.

VHS color signal reproduction processing circuit 32-A
Is the one excluding the comb filter 8 of FIG.
The output is connected to the other terminal V of the switch SW1. The switch SW2 has its midpoint connected to the output end of the comb filter 4, and one D side of the selected terminals is connected to the mixer 17. The V side of the other end of the switch SW2 is guided to the mixer 33. The switches SW1 and SW2 are switched in association with each other depending on the operating state of the dubbing VTR, as indicated by the selection terminal display of both.
That is, in both cases, the D side is dubbing from 8 mm to VHS, and the V side is VHS reproducing.

Next, the operation of dubbing from the reproducing VTR to the storing VTR will be described below. In the reproduction side VTR 50 of the 8 mm system, an electric signal is taken out from the recorded tape 10 by the rotary magnetic head 11 and amplified by the preamplifier 12 to a predetermined size. This output is a high pass filter (HPF) 13 and a low pass filter (LPF) 14 for separating a luminance signal and a color signal.
Given to. The high pass filter 13 is for separating the luminance signal, and the low pass filter 14 is for separating the color signal.

These outputs are connected to the luminance signal reproduction processing circuit 15 and the color signal reproduction processing circuit 16-A, respectively. The luminance signal reproduction processing circuit 15 demodulates the luminance signal and performs processing such as de-emphasis and noise canceller.
The color signal reproduction processing circuit 16-A converts the color signal component into the original frequency fSC. This signal is applied to the D terminal of the switch SW1 and input to the comb filter 4 for crosstalk removal. The color signal from which crosstalk has been removed is input to the switch SW2, is output to the terminal D side, is then guided to the mixer 17, is added to the brightness signal output of the brightness signal reproduction processing circuit 14, and is combined at the terminal 18. It is given as a video signal. On the other hand, the recording side VTR 51 of the VHS system
Then, the composite video signal applied to the terminal 18 is the low-pass filter (LPF) 19 and the band-pass filter (BP).
F) 21 separates a luminance signal and a chrominance signal.

The luminance signal is frequency-modulated by the luminance signal recording processing circuit 20 and subjected to processing such as emphasis.
The color signal is converted into a low frequency by the color signal recording processing circuit 22. These signals are mixed by the mixer 23, amplified by the recording amplifier 24, and passed through the magnetic head 25.
It is recorded on the magnetic tape 26. With the above, the dubbing operation is completed. In the VHS recording side VTR section 51 of this VHS system,
A reproduction signal processing circuit (27 to 34) for reproducing the dubbed signal or the recorded tape as described above is also provided.

27 is a rotary magnetic head, 28 is a preamplifier, 29 is a high-pass filter, 31 is a low-pass filter, 30 is a luminance signal reproduction processing circuit, and 32-A is a comb for removing crosstalk from the conventional color signal reproduction processing circuit 32. The color signal reproduction processing circuit without the shape filter, 33 is a mixer, and 34 is an output terminal. These operations are for the playback VTR
Since it is almost the same as the operation of 50, only the points related to this case will be described here.

The low-frequency conversion color signal of the video signal recorded on the magnetic tape 26 by the VHS system is converted to the original color signal frequency fSC by the color signal reproduction processing circuit 32-A, and then the switch SW1 is operated. It is applied to the V terminal and applied to the comb filter 4 for removing crosstalk. The color signal from which crosstalk has been removed is input to the switch SW2, output to the terminal V side, and then guided to the mixer 33, where V
It is added to the luminance signal output of the HS type luminance signal reproduction processing circuit 30 and given to the terminal 34 as a composite video signal.

As described above, the comb filter 4 for crosstalk removal can be commonly used for the reproduction of the 8 mm system and the reproduction of the VHS system, both of which are so-called color under, which is a low-pass conversion color. This is because the signal recording method is adopted. When a color signal is converted into a low frequency band in a high density recording system called azimuth recording, a sufficient amount of azimuth loss cannot be obtained at a low frequency band, so that crosstalk from an adjacent channel is also reproduced.

In order to efficiently remove this crosstalk, when the color signals are converted to the low frequency range, the 8 mm system is the PI system,
In the VHS system, color signal processing called the PS system is performed. In these methods, crosstalk (color signal crosstalk from adjacent channels) is canceled by a comb filter, and as a result, a color signal is reproduced. On the magnetic tape, the low-frequency conversion color signal frequency is different from the 8 mm system and the VHS system, respectively, but the original color signal frequency f is obtained by the color signal reproduction processing times.
After being converted to SC, that is, at the input of the comb filter for crosstalk removal, the original color signal frequency fSC including crosstalk (3.58 MHz in the case of NTSC signal) is obtained, so the same comb filter is used. Can be processed.

In the above example, an NTSC television signal for dubbing is described, but a PA different from this is used.
Dubbing VTR for processing L-system television signals
The same applies to. However, the specifications of the comb filters used differ due to the difference in the two methods.

[0025]

As described above, the conventional reproduction side VT is used.
Even if the comb filters for crosstalk removal in the reproduction color signal processing section used respectively in the R section and the recording side VTR section are integrated into one, the operation of the dubbing VTR can function in the same manner as in the past. Since it is possible and the number of parts can be reduced, the circuit can be simplified and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a video signal processing circuit of the present invention.

FIG. 2 is a block diagram of a video signal processing circuit of a conventional dubbing VTR.

3 is a detailed block diagram (A) of a color signal reproduction processing circuit of a reproduction side VTR section of FIG. 2 and a detailed block diagram (B) of a color signal reproduction processing circuit of a recording side VTR section of FIG.

[Explanation of symbols]

 10 ... Recorded tape 11, 27 ... Rotating magnetic head 12, 28 ... Preamplifier 13, 29 ... High pass filter 14, 19, 31 ... Low pass filter 15, 30 ... Luminance signal reproduction processing circuit 16, 32 ... Color signal reproduction processing circuit 17 , 33 ... Mixer 18, 34 ... Terminal 20 ... Luminance signal recording processing circuit 21 ... Band pass filter 22 ... Chromatic signal recording processing circuit 24 ... Recording amplifier 25 ... Magnetic head 26 ... Magnetic tape 50 ... Reproduction side VTR 51 ... Recording side VTR

Claims (1)

[Claims] 1. A video signal processing circuit of a dubbing tape recorder having a reproduction side tape recorder section and a recording side tape recorder section, wherein crosstalk removal used in a reproduction color signal processing section is provided in the video signal processing circuit. One comb filter for use is provided, input switching means is provided on the input side of the comb filter, and output switching means is provided on the output side, and the input switching means and the output switching means are for reproducing or recording on a tape recorder. The comb-shaped filter switches the input switching means and the output switching means in synchronism with each other to switch the signal from the tape recorder section on the reproducing side. When dubbing to the tape recorder on the side, it operates as a comb filter in the playback color signal processing unit for the tape recorder on the playback side. When reproducing the ring signal, the video signal processing circuit for dubbing videotape recorder, characterized in that to operate as a comb filter of the reproduced chrominance signal processor for recording side tape recorder.